On Wed, Aug 10, 2005 at 12:43:39PM -0400, Matt Clausen wrote:
> Yet when I do a backup to disk, I see decent performance
> on one stream (about 8,000KB/s or so) but the other streams will drop to
> around 300-500KB/s.
>
> NUMBER_DATA_BUFFERS = 16
> NUMBER_DATA_BUFFERS_DISK = 16
>
> SIZE_DATA_BUFFERS = 262144
> SIZE_DATA_BUFFERS_DISK = 1048576
>
> and I see this performance on both the master server disk pool AND a
> media server disk pool. The master server is a VxVM concat volume set of
> 3x73GB 10,000RPM disks and the media server is an external raid 5 volume
> of 16x250GB SATA disks.
I don't believe you're going to get good performance on a 16 member
RAID5 set of SATA disk. You should get better with a pair of 8 member
raid sets, but SATA is not fast disk and large raid 5 sets kill you on
write performance. If you're stuck with the SATA drives, configure them
as 3 4+1 RAID5 sets and use the 16th member as a hot spare. You'll have
3TB of disk staging instead of about 3.8TB but it will perform a lot
better.
--
Ed Wilts, Mounds View, MN, USA
mailto:ewilts AT ewilts DOT org
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